Translation of Festigkeit in German-English

In addition she is enjoying her studies very much. Work is fine! I'm in a learning phase and I have started my initial plans quickly. Two hours ago, I watched the Grand slam final of the US open!
The climb was much exhausting than I had presumed. I had forgotten that we were at high altitude where there is less oxygen and that every step required double effort. It was a great exercise.
I connected to a group of people and we played some volleyball, had some drinks and they told me a little about the place and the country in general. I returned to the hostel and took a cold shower.